In computing, a pointing device functions by detecting two-dimensional motion relative to its supporting surface. The pointing device sometimes features other elements, such as “wheels”, which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input. The motion of the pointing device typically translates into the motion of a pointer on a display, which allows for fine control of a Graphical User Interface (GUI). Typically these pointing devices utilize a “point and click” sequence of moving the cursor to the desired position and depressing a button to select an action.
There are several different styles of pointing devices such as a mouse, trackball, joystick, touchpad and the like. A mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. A mouse may sometimes features other elements, such as “wheels”, which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input.
A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on graphical workstations for easy precision.
A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer.
A touchpad is a pointing device consisting of specialized surface that can translate the motion and position of a user's fingers to a relative position on screen. Touchpads are a common feature of laptop computers and also used as a substitute for a computer mouse where desk space is scarce. Touchpads can also be found on personal digital assistants (PDAs) and some portable media players, such as the iPod® using a click wheel.